1. Field of the Invention
The present invention relates to a zoom lens, which is particularly suitable as a photographic optical system such as a video camera, a camera for silver-salt film, a digital camera, or the like.
2. Description of the Related Art
When photographing an object, if vibration occurs in a photographic system, blurring occurs in the photographic image. In order to solve this problem, various types of image stabilizing optical systems, including image stabilizing performance for preventing blurring from occurring in photographic images, have been proposed.
Many zoom lenses serving as photographic systems have been known wherein a part of a lens unit is displaced, thereby correcting image blurring.
A zoom lens has been known wherein with a zoom lens having a four-group configuration consisting of first, second, third, and fourth lens units having positive, negative, positive, and positive refractive power in order from the object side to the image side, a part of the third lens unit is vibrated in the direction perpendicular to the optical axis, thereby obtaining a still image.
A zoom lens has been known wherein the third lens unit is divided into a lens unit having negative refractive power and a lens unit having positive refractive power, and the lens unit having positive refractive power is vibrated in the direction perpendicular to the optical axis, thereby obtaining a still image. For example, such a zoom lens has been described in Japanese Patent Laid-Open No. 7-128619, U.S. Pat. No. 6,473,231, Japanese Patent Laid-Open No. 2002-244037, and Japanese Patent Laid-Open No. 2003-322795.
In general, with a photographic system for stabilizing an image by subjecting a part of a lens unit of the photographic system to shift decentration, there is an advantage wherein there is no need to provide a particular optical system for stabilizing an image.
However, this also includes a problem wherein there is the need to provide space for a lens unit to be moved, and also a decentration aberration occurs at the time of image stabilizing.
In recent years, with video cameras, digital cameras, and so forth, there is a demand for a reduction in the overall size of the camera, while yielding a high quality image. Therefore, there is a demand for a zoom lens wherein decentration aberration can be minimized at the time of image stabilizing.